Card Mechanic I have always loved the thought of

I am not sure if anybody has played a game with this mechanic, but ...

I have always loved the idea of a reshuffle card in a play deck. The card gets drawn and immediately the discard pile and play deck are reshuffled. I always figured it would be good to stop players playing the odds in predictable decks, such as event decks.

almost every TCG made has some variable of the deck shuffling card. There are dozens in Magic. As far as in board games, I can't think of any off the cuff, but could be quite interesting if you can figure out a way to use it as a more central design to a game then as a one off card.

In the Settlers of Catan card game the.. get this, events deck(!!!) ^_^ works exactly as you've described. Within it is a card named Year's End which has you shuffle the deck. I like it, because you may know all the cards that are in the deck, but you don't know when that Year's End is coming.

so it is not new, the best thing being that it is an already established mechanic, so adding it to a game is already palatable. Just proves that most ideas are not new, we just need to fine new ways to apply old idea's.